Walmart has an extensive blockchain through which they can trace the quality of products all the way from suppliers to their warehouses. Every time products move through the supply chain, a quality figure is inscribed in a block. So if a customer complains about a certain product as damaged, it is much easier to determine where in the supply chain the product was spoiled. This helps Walmart locate trouble areas on their supply chains and address them which in turn ameliorates customer service and curbs the rate of returns and refunds.